Because of the increasing use of electronics, for instance, in the control of engines, especially in motor vehicles, error diagnoses are becoming steadily more costly. This makes it meaningful to investigate possible errors in the system, using a chain diagnosis running on an external computer. In order to be able to model such an active chain, it is known, for instance, that one may carry out a simulation of both systems (the system to be examined and the program for setting up the active chain) on a computer, an adjustment of the computing speeds being necessary in this case. This causes a very great expenditure, since both the control unit software and a model of the system have to be implemented on the computer. However, because of this, the system behavior is also influenced, so that the knowledge obtained can only be transferred conditionally to the original.
For the design approach to treating the problems going together with this, it is known that one may slow down the running of the faster system, for instance, via the CPU clock, while using an original control unit. On the other hand, it is possible, in a limited fashion, to speed up the running of the slower system, for instance, by making available more efficient computers. But the problem always remains that the original behavior is not achieved 100%, and a considerable adjustment expenditure is created.